--- loncom/xml/lontexconvert.pm	2006/10/24 01:28:47	1.80
+++ loncom/xml/lontexconvert.pm	2008/01/29 11:04:10	1.85
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # TeX Conversion Module
 #
-# $Id: lontexconvert.pm,v 1.80 2006/10/24 01:28:47 albertel Exp $
+# $Id: lontexconvert.pm,v 1.85 2008/01/29 11:04:10 foxr Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -85,6 +85,7 @@ $Apache::lontexconvert::messedup=0;
 # into the safe space since opcode checks only occur at compile time
 sub convert_real {
     my ($texstring)=@_;
+    &Apache::lonnet::logthis("convert_real converting '$$texstring");
     my ($xmlstring,$errorstring);
     local $SIG{SEGV}=sub { $Apache::lontexconvert::messedup=1; die; };
     local $SIG{ALRM}=sub { 
@@ -95,12 +96,14 @@ sub convert_real {
     };
     &Apache::lonxml::start_alarm();
     if ($env{'browser.mathml'}) {
+	&Apache::lonnet::logthis("mathml translation");
 	$xmlstring=&tth::ttm($$texstring);
 	$xmlstring=~s/\<math\>/\<math xmlns=\"\&mathns\;\"\>/g;
 	$xmlstring=~s/\<br\>/\<br\/\>/g;
 	$xmlstring=~s/\<p\>/\<p\>\<\/p\>/g;
 	$errorstring.=&tth::ttmerror();
     } else {
+	&Apache::lonnet::logthis("tth translation");
 	$xmlstring=&tth::tth($$texstring);
 	$errorstring.=&tth::ttherror();
 	$xmlstring=~s-</font(\s*)>-</font>-g;
@@ -108,6 +111,14 @@ sub convert_real {
     $xmlstring=~s/^\s*\<br clear\=\"all\"/\<br/s;
     $xmlstring=~s/^\s*//;
     $xmlstring=~s/\s*$//;
+    #
+    # \rightleftharpoons is not converted by tth but maps
+    # reasonably well to &#8660;.  If we get many more of these,
+    # we're going to need to have a translation sub.
+    #
+    $xmlstring=~s/\\rightleftharpoons/\&\#8660;/g;
+
+    &Apache::lonnet::logthis("Final result: $xmlstring");
     &Apache::lonxml::end_alarm();
     return ($xmlstring,$errorstring);
 }
@@ -151,7 +162,7 @@ ENDCONV
 
 sub clean_out_math_mode {
     my ($texstring)=@_;
-    $$texstring=~s/(?!\\)\$//g;
+    $$texstring=~s/(?<!\\)\$//g;
     $$texstring=~s/\\[\)\(\]\[]//g;
     $$texstring=~s/\\ensuremath//g;
     return '';
@@ -200,15 +211,35 @@ sub jsMath_converted {
     sub jsMath_process {
 	my $state = pop(@jsMath_sent_header);
 	return '' if !$state;
-	return '<script type="text/javascript">jsMath.Process()</script>';
+	return "\n".
+	    '<script type="text/javascript">jsMath.Process()</script>'."\n";
+    }
+    sub jsMath_state {
+	my ($level) = @_;
+	return $jsMath_sent_header[$level];
+    }
+}
+
+sub tex_engine {
+    if (exists($env{'form.texengine'})) {
+	return $env{'form.texengine'};
+    }    
+    if ($env{'request.course.id'}
+	&& exists($env{'course.'.$env{'request.course.id'}.'.texengine'})) {
+	return $env{'course.'.$env{'request.course.id'}.'.texengine'};
+    }
+    if (exists($env{'environment.texengine'})) {
+	return $env{'environment.texengine'};
     }
+    return 'tth';
 }
 
 sub init_math_support {
+    my ($inherit_jsmath) = @_;
     &init_tth();
     &Apache::lontexconvert::jsMath_push();
-    if ($env{'environment.texengine'} eq 'jsMath' ||
-	$env{'form.texengine'}        eq 'jsMath' ) {
+    if (lc(&tex_engine()) eq 'jsmath' ||
+	($inherit_jsmath && &jsMath_state(-2))) {
 	return &Apache::lontexconvert::jsMath_header();
     }
     return;
@@ -232,7 +263,7 @@ sub mimetex_converted {
 
 sub converted {
     my ($string,$mode)=@_;
-    if ($mode eq '') { $mode=$env{'environment.texengine'}; }
+    if ($mode eq '') { $mode = &tex_engine(); }
     if ($mode =~ /tth/i) {
 	return &tth_converted($string);
     } elsif ($mode =~ /jsmath/i) {